Running the engine to charge batteries - gear for load or no gear?

[goboatingnow]

Older engines had less of a problem. Newer higher compression engines especially when new can suffer glazing from slow speed low load running. The problems don’t often appear obvious but , blow by ( with oil in fuel or fuel in the oil ) excessive ring wear , excessive oil consumption

The problem doesn’t lead to terminal engine decline, especially if you use the engine for its intended purpose regularly

Diesels like to used hard.

[PineyWoodsPete]

Originally Posted by mvmojo

Full time live-aboards in the Caribbean at anchor for 6 years. Ran our Lehman diesel in neutral 1 hr in the morning and 1 hr at night every day to charge batteries and run engine driven refrigeration. No problems.

If you mean standard idle @ 5-700 RPM, not "fast idle" allowing any speed in "N", this is by far the most inefficient way to charge batteries. In my past diesels - Yanmar, Westerbeke, Volvo - I always ran @ 1500-1800RPM for max alternator output, which was minimal at true idle speed.

My current common-rail VW 165TDi requires 2000RPM (of 4000 max) to get the hybrid in-line 7kW/5kW motor/gen up to max output of 100A@ 48V into the 11.5kWh LiPo. At true idle of 850 RPM ~5A.

[valhalla360]

Originally Posted by twig

I don’t buy into that theory. . Look at the millions of semis idling all night in all the truck stops and rest area around the world. If it was that bad they would find another way to keep ac or heater on.

That's 8hr at light load followed by 8-12hr under heavy variable load.

This is different than many cruisers who may anchor for weeks or even months only using the engine to charge batteries.

If you charge for a few days followed by a few hours motoring to the next anchorage under a pretty good load, it's not likely to be an issue.

[Sam Woodbridge]

Originally Posted by DEAN2140

"In the Yanmar manual it does state to run the engine at wide open throttle for thirty minutes for ever ten or so hours of cruising"

Can you post a copy or give me a link?

I took a screen shot with my phone of the manual. I’m going to try and upload it.

[Macdoug]

Originally Posted by Sam Woodbridge

I took a screen shot with my phone of the manual. I’m going to try and upload it.

This doesn’t say you should run the engine at WOT for 30 minutes every ten hours. It says you shouldn’t run at WOT for more than 5% of the time (because the engine isn’t designed to spend a lot of time at WOT). I certainly wouldn’t run my engine flat out for 30mins straight unless it was an emergency.

[chasfgr]

Originally Posted by George_SD

Fair enough, but solar is not something I can do in a very short order before my next trip where I will need to recharge using the engine.

So the question remains

Motor sail - but to get any drive you need a self-pitching prop, which few have (see Brunton Autoprop).


It is common-sense to have sufficient solar to cover your normal daily use at anchor. That's fairly easy in summer in the Med, and not too difficult even as far N as 60 degrees.

[wingssail]

We run the engine (Yanmar 3JH) to charge the batteries. Our 270 watts of solar helps with our daily electrical needs but the engine charging is essential for us.

We have been doing this whenever we've been off the dock with this engine for 28 years. The engine now has 6700 hours.

In hot climates where refer/freezer electrical load is high we run the engine at 2000rpm for 1.5 hours daily and produce about 110AH with our Balmar 110A alternator and Balmar ARS-5 regulator using all default settings. In colder water we need less engine charging time.

We've had no obvious problems with carbon build up, the insides of the engine are clean, the exhaust elbow is clear, and the engine starts and runs fine, does not smoke, etc. We've had a few oiling questions but nothing was found that needed work. So we think that using the engine to charge the batteries does no obvious harm.

I'd love to be able to avoid using the engine for this because without charging we'd have only about 2200 hours on the engine but adding more solar means an arch and quite a bit of weight and windage right where I don't want it, same with a genset, so this has been our approach.

[MikeTC]

Originally Posted by GoneDiving

Seems like a lot of faffing around for very little gain.



30A @ 12vdc is 360w or 10% of my $500 elcheapo generator. Put another way, every hour of mains engine wear and tear and issues from low/no load could be replaced with barely 10 minutes of Genset use.

I totally agree. Coupled with a smart charger.

[Shanachie]

I'm puzzled by this thread. You can install 350 watts or so of solar in an afternoon. That would give you 10 to 18 amps of charge every hour of sunlight. Why do you need to run your diesel?


Running your diesel to charge batteries is a rookie movie, except under unusual circumstances. Use the available technology to do what you have to do.

[night0wl]

Marine engine rebuild - $3000
New marine engine due to excessive hours/glazing/low load - $12k minimum
New el-cheapo inverter generator to use for battery charging: $500

Given these economics, I've stopped using my engine to charge my batteries. I fire up the generator, lay out the shorepower, power up my onboard battery charger, and 20 amps flow into my batteries with the generator in eco-mode. The generator is relative quiet...even moreso when I drop it into the dinghy and float it behind the boat on calmer days/mornings.

Downside is I have to carry gasoline and worry about Carbon Monoxide (CO). However, its quieter and I dont worry about burning out alternators or glazing cylinders. Also, the Honda knock-offs are getting to be under $400 now. My next goal is to rig up a propane carburetor to eliminate the need of carrying an additional fuel source...although I'm carrying gasoline aboard for the dinghy engine anyway. Maybe a propane conversion for the Merc 5 hp 2 stroke too??? Or if someone would productionize a compact genset and slap it on this engine from this

[wingssail]

Originally Posted by Shanachie

I'm puzzled by this thread. You can install 350 watts or so of solar in an afternoon. That would give you 10 to 18 amps of charge every hour of sunlight. Why do you need to run your diesel?

Running your diesel to charge batteries is a rookie movie, except under unusual circumstances. Use the available technology to do what you have to do.

Shanachie, I take exception to that comment. I cannot install any additional solar in an afternoon or in any acceptable amount of time without changing the whole character of my boat. I have no arch and no wish to have one. I have no cabin top on which to place solar and no bimini either. None of these are easy for me to change, and besides, my boat serves a purpose which would be completely sacrificed by the changes required to add 350 watts of solar. I like my boat for what it is and I don't wish to change it to something else in order to carry a solar array that would produce 160AH per day (my standard daily usage).

And beyond that, I might not be as advanced as you obviously are, technologically, but I'm not a rookie. I've been doing this for 50 years and I think I am moderately switched on. Our choices for our boat, related to battery charging and electrical usage, are well thought out and appropriate for what we are doing with our boat, which is: living aboard, AND cruising long distances safely and quickly, AND sailing excellently, AND winning races.

Tell me how your charging solutions would meet my needs better than my "rookie" solutions do.

[wingssail]

Originally Posted by night0wl

Marine engine rebuild - $3000
New marine engine due to excessive hours/glazing/low load - $12k minimum
New el-cheapo inverter generator to use for battery charging: $500

Given these economics, I've stopped using my engine to charge my batteries. I fire up the generator, lay out the shorepower, power up my onboard battery charger, and 20 amps flow into my batteries with the generator in eco-mode. The generator is relative quiet...even moreso when I drop it into the dinghy and float it behind the boat on calmer days/mornings.

Downside is I have to carry gasoline and worry about Carbon Monoxide (CO). However, its quieter and I dont worry about burning out alternators or glazing cylinders. Also, the Honda knock-offs are getting to be under $400 now. My next goal is to rig up a propane carburetor to eliminate the need of carrying an additional fuel source...although I'm carrying gasoline aboard for the dinghy engine anyway. Maybe a propane conversion for the Merc 5 hp 2 stroke too??? Or if someone would productionize a compact genset and slap it on this engine from this

1. And how do you demonstrate that charging batteries will require a new engine?
2. Supposing a quite conservative daily electrical load of, say, 150amphours per day, at 20amps, how many hours do you intend to run that generator?
3. Oh, you'll let it out on a painter in the dingy behind you boat? I'll bet your neighbors will love that
4. Run your generator (and outboard) on propane? Have you calculated how many gallons of propane it takes to provide the same energy as gasoline? (I'll bet not) and where do you think you will get all that propane?
5. And you fire up your portable generator, which I assume you carry on deck, and lay out cables each day to do it, then run it for hours, so you're really ready to get underway quickly if weather demands? I'd guess not, plus your decks must be real clear with all that stuff sitting around, kind of like a Beverly Hilbilly's arrangement, right?
6. And, did you ever consider that someone might not want to have the weight and space of a portable generator and the assorted cables nor the lack of seaworthiness of a deck covered with all your "stuff" and clutter? I guarantee that thought has not entered your head.

[Snerf1]

Originally Posted by GoneDiving

Seems like a lot of faffing around for very little gain.

30A @ 12vdc is 360w or 10% of my $500 elcheapo generator. Put another way, every hour of mains engine wear and tear and issues from low/no load could be replaced with barely 10 minutes of Genset use.

We have a winner. 2k watt (portable) generators were designed to mainly recharge golfcart batteries. 2.3k, 3k and up are useful for also actually running a/c tools and appliances.

1 hr daily in economy mode (under 55 dbs) is usually enough to bring a 220ah bank up to full charge. 1 gallon of gas is good for 10 hrs in economy mode.

An engine was designed to propel a vessel or vehicle along with some peripheral devices (eg alternator). Torque, rpm, gearing, horsepower, load, etc are design elements of running the motor.

So, while it is very useful to run an engine each day or so, it should be primarily for just running the engine. (Lubrication, bearings, seals, cooling, etc)

Sure, you can get some amps out of it, but if you run it for say 15 min, youll just be primarily charging the starting battery anyway.

The shunt only comes into play as the diode redirects to the house bank after the primary is satisfied. Compare that to a generator which can be attached either direct dc to the batteries, or ac thru the shore power converter.

A small honda or yamaha with 400-500 watts solar is the optimal setup. You only need a 1-2 gallons of gas for 10-20 hrs run time, which can be stored in a well ventilated area.

With this set up, you can keep 220ah at 100% pratically everyday. Right tool for the right job. Let solar do its thing, but dont be a slave to weather when the whisper quiet genset can fill in when necessary.

[capblasters]

For what it's worth, we run the engine in neutral with the gear shift in the reverse position to set the throttle. Why reverse? Only because once in a rush one of the crew throttled it in forward without making sure the neutral bypass was in place. Soon thereafter the anchor alarm sounded as we motored past our anchor. Lesson learned was check, recheck and cross-check the neutral setting after you've throttled up. Throttling up in reverse after putting in neutral at least may drag but not unset your anchor.

[wingssail]

Originally Posted by Snerf1

...Sure, you can get some amps out of it, but if you run it for say 15 min, youll just be primarily charging the starting battery anyway.

The shunt only comes into play as the diode redirects to the house bank after the primary is satisfied. Compare that to a generator which can be attached either direct dc to the batteries, or ac thru the shore power converter...

You are making a lot of assumptions there, fella. Like that every boat has a diode/shunt device to charge both start and house batteries, and like every boat starts the engine on the "start' battery. And more, like that direct DC or AC shore power converter directs power to the batteries any differently.

A small honda or yamaha with 400-500 watts solar is the optimal setup. You only need a 1-2 gallons of gas for 10-20 hrs run time, which can be stored in a well ventilated area.

IF one wants to carry a portable genset, and IF they have room for 400-500watts of solar.

With this set up, you can keep 220ah at 100% pratically everyday. Right tool for the right job. Let solar do its thing, but dont be a slave to weather when the whisper quiet genset can fill in when necessary.

It's a bit more than a whisper when your neighbors can hear it 100 yards away

You see, Snerf1, Not everyone has the same job to perform, and not everyone's boat has the same job to fulfill. What the right tool is for your boat's job may be the exact wrong tool for my boat's job. Try to keep an open mind.